Test System with Hopper Equipment

ABSTRACT

A test system may be provided in which devices under test (DUTs) are loaded into test trays. Test trays may be moved between test stations using a test conveyor belt. The test system may include loading equipment for placing test trays on the test conveyor belt at desired intervals. The loading equipment may include a feed conveyor belt, tray support structure, and at least one computer-controlled grabber. Test trays may be placed on the feed conveyor belt by test personnel or automated loader. The grabber may be used to transport an incoming test tray from the feed conveyor belt to the support structure. The test tray may be temporarily docked at the support structure. The grabber may then transport the test tray from the support structure to the test conveyor belt so that the DUT on the test tray can be passed to the various test stations for testing.

This application claims the benefit of provisional patent applicationNo. 61/595,572, filed Feb. 6, 2012, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

This relates generally to automation, and more particularly, toautomated equipment for use in manufacturing operations such as testing.

Electronic devices are often tested following assembly to ensure thatdevice performance meets design specifications. For example, a devicemay be tested at a series of test stations to ensure that components andsoftware in the device are operating satisfactorily. At each teststation, an operator may couple a device to test equipment using acable. Following successful testing at all test stations, a device maybe shipped to an end user.

The process of attaching and detaching test cable connectors and themanual operations associated with performing tests at test stations canbe cumbersome and burdensome to test system operators. If care is nottaken, tests may be less accurate and more time consuming than desired.

It would therefore be desirable to be able to provide improved ways ofperforming manufacturing operations such as testing operations onelectronic devices.

SUMMARY

A test system may be provided in which devices under test are loadedinto test trays. Test trays in the test system may be tested at teststations. A test conveyor belt may be used to move test trays from onetest station to another. The test system may include loading equipmentfor placing test trays onto the test conveyor belt at predeterminedintervals.

In one suitable arrangement, the loading equipment may include a feedconveyor belt, a fixed support structure, and a computer-controlledloader. A test operator or automated test tray loader may provide testtrays to the feed conveyor belt. A safety wall may be placed above thefeed conveyor belt so that only a single test tray may pass between anupper surface of the feed conveyor belt and a lower surface of thesafety wall at any given time. A first sensor associated with the feedconveyor belt may be used to determine when an incoming test tray isavailable for pickup.

The loader may be used to move an incoming test tray from the feedconveyor belt to the fixed support structure. In particular, the loadermay include loader engagement features configured to mate withcorresponding test tray engagement features in the test tray. A secondsensor (e.g., a radio-frequency identification sensor) may be used toidentify a serial number associated with each test tray beingtransferred from the feed conveyor belt to the fixed support structure.

The test tray may be stored temporarily on the fixed support structure.More than one test tray may be stored on the fixed support structure.Sensors associated with the fixed support structure may be used todetermine whether the fixed support structure is capable of receivingadditional test trays from the test conveyor belt (e.g., whether thefixed support structure has a vacant test tray spot or whether the fixedsupport structure is fully occupied by test trays).

The loader may be directed to move a selected test tray from the fixedsupport structure to the test conveyor belt. The rate at which testtrays are deposited on the fixed support structure may at most be equalto the rate at which test trays are transferred from the fixed supportstructure to the test conveyor belt. In another suitable arrangement,the test system may include an additional computer-controlled loaderthat is used to move a selected test tray from the fixed supportstructure to the test conveyor belt.

Further features of the present invention, its nature and variousadvantages will be more apparent from the accompanying drawings and thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device suchas a handheld device of the type that may be manufactured usingautomated equipment in accordance with an embodiment of the presentinvention.

FIG. 2 is a schematic diagram of an illustrative electronic device withinput/output devices and wireless communications circuitry in accordancewith an embodiment of the present invention.

FIG. 3 is a diagram of manufacturing equipment of the type that may beused in manufacturing an electronic device in accordance with anembodiment of the present invention.

FIG. 4A is an exploded perspective view of an illustrative device undertest, pad extender, and test tray in accordance with an embodiment ofthe present invention.

FIG. 4B is a perspective view of an illustrative device under test, padextender, and test tray in accordance with an embodiment of the presentinvention.

FIG. 5A is a top perspective view of an illustrative test tray inaccordance with an embodiment of the present invention.

FIG. 5B is a bottom perspective view of an illustrative test tray inaccordance with an embodiment of the present invention.

FIG. 5C is a perspective view of an illustrative test tray in which adevice under test has been mounted in accordance with an embodiment ofthe present invention.

FIG. 6 is a diagram of a portion of a test system in which test traysare automatically moved from a first conveyor to a pedestal and from thepedestal to a second conveyor in accordance with an embodiment of thepresent invention.

FIG. 7 is a top view of the first conveyor belt in showing how a testtray on the first conveyor belt may be picked up by a first device undertest grabber in accordance with an embodiment of the present invention.

FIG. 8 is a cross-sectional side view of a device under test grabber armthat has engaged a mating test tray in accordance with an embodiment ofthe present invention.

FIG. 9 is a perspective view of a device under test grabber arm that isholding a test tray in accordance with an embodiment of the presentinvention.

FIGS. 10 and 11 are perspective views of a test system in which a firstloader is being used to load test trays onto a pedestal while a secondloader is being used to load test trays onto a conveyor from thepedestal in accordance with an embodiment of the present invention.

FIGS. 12-14 are perspective views of a test system in which a singleloader is used to load test trays onto a pedestal and to load test traysonto a conveyor from the pedestal in accordance with an embodiment ofthe present invention.

FIG. 15 is a flow chart of illustrative steps involved in operating thetest system of FIG. 6 in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

Electronic devices such as electronic device 10 of FIG. 1 may bemanufactured using automated manufacturing equipment. The automatedmanufacturing equipment may include equipment for assembling devicecomponents together to form an electronic device. The automatedmanufacturing equipment may also include testing systems for evaluatingwhether devices have been properly assembled and are functioningproperly.

Devices such as device 10 of FIG. 1 may be assembled and tested using anautomated manufacturing system. The manufacturing system may include oneor more stations such as one or more test stations for performingtesting operations.

Devices that are being tested in a test system may sometimes be referredto as devices under test (DUTs). Devices under test may be provided tothe test stations using a conveyor belt, using robotic arms, or usingother loading equipment.

Any suitable device may be tested using test equipment. As an example,device 10 of FIG. 1 may be tested. Device 10 may be a computer monitorwith an integrated computer, a desktop computer, a television, anotebook computer, other portable electronic equipment such as acellular telephone, a tablet computer, a media player, a wrist-watchdevice, a pendant device, an earpiece device, other compact portabledevices, or other electronic equipment. In the configuration shown inFIG. 1, device 10 is a handheld electronic device such as a cellulartelephone, media player, navigation system device, or gaming device.

As shown in FIG. 1, device 10 may include a housing such as housing 12.Housing 12, which may sometimes be referred to as a case, may be formedof plastic, glass, ceramics, fiber composites, metal (e.g., stainlesssteel, aluminum, etc.), other suitable materials, or a combination ofthese materials. In some situations, parts of housing 12 may be formedfrom dielectric or other low-conductivity material. In other situations,housing 12 or at least some of the structures that make up housing 12may be formed from metal elements.

Device 10 may, if desired, have a display such as display 14. Display 14may be a touch screen that incorporates capacitive touch electrodes ormay be insensitive to touch. Display 14 may include image pixels formedfrom light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells,electrophoretic display elements, electrowetting display elements,liquid crystal display (LCD) components, or other suitable image pixelstructures. A cover glass layer may cover the surface of display 14.Openings for buttons such as button 20, openings for speaker ports suchas speaker port 22, and other openings may be formed in the cover layerof display 14, if desired.

The central portion of display 14 (i.e., active region 16) may includeactive image pixel structures. The surrounding rectangular ring-shapedinactive region (region 18) may be devoid of active image pixelstructures. If desired, the width of inactive region 18 may be minimized(e.g., to produce a borderless display).

Device 10 may include components such as front-facing camera 24. Camera24 may be oriented to acquire images of a user during operation ofdevice 10. Device 10 may include sensors in portion 26 of inactiveregion 18. These sensors may include, for example, aninfrared-light-based proximity sensor that includes an infrared-lightemitter and a corresponding light detector to emit and detect reflectedlight from nearby objects. The sensors in portion 26 may also include anambient light sensor for detecting the amount of light that is in theambient environment for device 10. Other types of sensors may be used indevice 10 if desired. The example of FIG. 1 is merely illustrative.

Device 10 may include input-output ports such as port 28. Port 28 mayinclude audio input-output ports, analog input-output ports, digitaldata input-output ports, or other ports.

Sensors such as the sensors associated with region 26 of FIG. 1, camerassuch as camera 24, buttons such as button 20, and ports such as port 28may be located on any suitable portion of device housing 12 (e.g., afront housing face such as a display cover glass portion, a rear housingface such as a rear planar housing wall, sidewall structures, etc.). Forexample, buttons such as button 21 may be located on a sidewall portionof housing 12.

A schematic diagram of an electronic device such as electronic device 10is shown in FIG. 2. As shown in FIG. 2, electronic device 10 may includestorage and processing circuitry 27. Storage and processing circuitry 27may include storage such as hard disk drive storage, nonvolatile memory(e.g., flash memory or other electrically-programmable-read-only memoryconfigured to form a solid state drive), volatile memory (e.g., staticor dynamic random-access-memory), etc. Processing circuitry may be basedon one or more microprocessors, microcontrollers, digital signalprocessors, baseband processors, power management units, audio codecchips, application specific integrated circuits, etc.

Storage and processing circuitry 27 may be used to run software ondevice 10, such as internet browsing applications,voice-over-internet-protocol (VOIP) telephone call applications, emailapplications, media playback applications, operating system functions,etc. To support interactions with external equipment, storage andprocessing circuitry 27 may be used in implementing communicationsprotocols. Communications protocols that may be implemented usingstorage and processing circuitry 27 include internet protocols, wirelesslocal area network (WLAN) protocols (e.g., IEEE 802.11protocols—sometimes referred to as WiFi®), protocols for othershort-range wireless communications links such as the Bluetooth®protocol, cellular telephone protocols, etc.

Circuitry 27 may be configured to implement control algorithms thatcontrol the use of antennas in device 10. For example, to supportantenna diversity schemes and MIMO schemes or beam forming or othermulti-antenna schemes, circuitry 27 may perform signal qualitymonitoring operations, sensor monitoring operations, and other datagathering operations and may, in response to the gathered data, controlwhich antenna structures within device 10 are being used to receive andprocess data. As an example, circuitry 27 may control which of two ormore antennas is being used to receive incoming radio-frequency signals,may control which of two or more antennas is being used to transmitradio-frequency signals, may control the process of routing incomingdata streams over two or more antennas in device 10 in parallel, etc.

Input/output circuitry 29 may be used to allow data to be supplied todevice 10 and to allow data to be provided from device 10 to externaldevices. Input/output circuitry 29 may include input/output devices 31.Input/output devices 31 may include touch screens, displays withouttouch sensor capabilities, buttons, joysticks, click wheels, scrollingwheels, touch pads, key pads, keyboards, microphones, speakers, tonegenerators, vibrators, cameras, sensors, light-emitting diodes and otherstatus indicators, light sources, audio jacks and other audio portcomponents, data ports, light sensors, motion sensors (accelerometers),capacitance sensors, proximity sensors, etc. A user can control theoperation of device 10 by supplying commands through input/outputdevices 31 and may receive status information and other output fromdevice 10 using the output resources of input/output devices 31.

Wireless communications circuitry 33 may include radio-frequency (RF)transceiver circuitry formed from one or more integrated circuits, poweramplifier circuitry, low-noise input amplifiers, passive RF components,one or more antennas, transmission lines, and other circuitry forhandling RF wireless signals. Wireless signals can also be sent usinglight (e.g., using infrared communications).

Wireless communications circuitry 33 may include satellite navigationsystem receiver circuitry 35, transceiver circuitry such as transceivercircuitry 37 and 39, and antenna circuitry such as antenna circuitry 41.Satellite navigation system receiver circuitry 35 may be used to supportsatellite navigation services such as United States' Global PositioningSystem (GPS) (e.g., for receiving satellite positioning signals at 1575MHz) and/or other satellite navigation systems.

Transceiver circuitry 37 may handle 2.4 GHz and 5 GHz bands for WiFi®(IEEE 802.11) communications and may handle the 2.4 Bluetooth®communications band. Circuitry 37 may sometimes be referred to aswireless local area network (WLAN) transceiver circuitry (to supportWiFi® communications) and Bluetooth® transceiver circuitry. Circuitry 33may use cellular telephone transceiver circuitry (sometimes referred toas cellular radio) 39 for handling wireless communications in cellulartelephone bands such as bands at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz,and 2100 MHz or other cellular telephone bands of interest.

Examples of cellular telephone standards that may be supported bywireless circuitry 33 and device 10 include: the Global System forMobile Communications (GSM) “2G” cellular telephone standard, theEvolution-Data Optimized (EVDO) cellular telephone standard, the “3G”Universal Mobile Telecommunications System (UMTS) cellular telephonestandard, the “3G” Code Division Multiple Access 2000 (CDMA 2000)cellular telephone standard, and the “4G” Long Term Evolution (LTE)cellular telephone standard. Other cellular telephone standards may beused if desired. These cellular telephone standards are merelyillustrative.

Wireless communications circuitry 33 may include circuitry for othershort-range and long-range wireless links if desired. For example,wireless communications circuitry 33 may include wireless circuitry forreceiving radio and television signals, paging circuits, etc. In WiFi®and Bluetooth® links and other short-range wireless links, wirelesssignals are typically used to convey data over tens of hundreds of feet.In cellular telephone links and other long-range links, wireless signalsare typically used to convey data over thousands of feet or miles.

Wireless communications circuitry 33 may include one or more antennas41. Antennas 41 may be formed using any suitable antenna type. Forexample, antennas 41 may include antennas with resonating elements thatare formed from loop antenna structures, patch antenna structures,inverted-F antenna structures, slot antenna structures, planarinverted-F antenna structures, helical antenna structures, hybrids ofthese designs, etc. Different types of antennas may be used fordifferent bands and combinations of bands. For example, one type ofantenna may be used in forming a local wireless link antenna and anothertype of antenna may be used in forming a remote wireless link antenna.

FIG. 3 is a diagram of an illustrative system of the type that may beused for manufacturing operations such as device testing. As shown inFIG. 3, system 30 may include one or more stations such as test stations36. In general, test system 30 may include automated equipment that isused in loading and unloading devices under test, in conveying devicesunder test between test stations, and in performing tests andmaintaining a database of test results. Each test station 36 may, forexample, include test equipment for performing one or more tests ondevice under test 10. For example, a first type of test station 36 mayhave equipment for testing a display in DUT 10. A second type of teststation 36 may have equipment for testing an audio component in DUT 10.Yet another type of test station 36 may have equipment for testing lightsensors in DUT 10. Yet another type of test station 36 may haveequipment for testing wireless communications circuitry in DUT 10. Ifdesired, test system 30 may include more than one test station of thesame type arranged along conveyor belt 38 so that multiple DUTs can betested in parallel.

Device under test 10 may, if desired, be installed in a test tray suchas tray 32. Tray 32 may be configured to receive one or more devicesunder test. For example, tray 32 may have multiple slots, each of whichis configured to receive a corresponding device under test. If desired,tray 32 may be configured to receive only a single device under test.

Device 10 may be installed in test tray 32 manually or using automatedequipment. To facilitate manual installation, test tray 32 may includefeatures to facilitate human manipulation. For example, test tray 32 mayinclude features that help an operator open and close clamps or otherdevice holding features in test tray 32. Device under test 10 that ismounted in test tray 32 may be conveyed between test stations 36 using aconveyor belt such as conveyor belt 38 (e.g., a belt that moves indirection 40). DUT 10 may be tested using at least some of test stations36 as DUT 10 travels down conveyor belt 38.

It may be desirable to regulate the rate at which devices under test areplaced on conveyor 38 in system 30. Test system 30 may include loadingequipment such as loading equipment 200 configured to place test trays32 on conveyor belt 38 so that test trays 32 are not spaced too closelyor too far apart from one another. With this type of arrangement, testtray 32 may serve as an interface between DUT 10 and loading equipment200. Test tray 32 may, for example, be more robust than DUT 10, may haveengagement features that are configured to mate with loading equipment200, may have an identification number that facilitates tracking, andmay have other features that facilitate loading of DUT 10 onto conveyorbelt 38.

For example, loading equipment 200 may be provided with one or morecomputer-controlled positioning arms. The positioning arms in loadingequipment 200 may be used in picking up a test tray (i.e., a test traythat is loaded with DUT 10) that is provided from a test operator,placing the test tray on a temporary test tray dock, picking up the testtray from the temporary test tray dock at a later point in time, andthen placing the test tray on conveyor belt 38 for testing. Handlingtest trays 32 in this way serves to synchronize the rate at which thetest operator provides test trays 32 to loading equipment 200 with therate at which the automated positioning arms in loading equipment 200place test trays 32 on conveyor belt 38 for optimal test throughput.

Using the system of FIG. 3, an operator may place test trays 32 on afeed conveyor belt that is part of loading equipment 200. Test trays 32may be sequentially loaded onto conveyor belt 38 at predetermined timeintervals so that DUT 10 on each test tray 32 can be tested using teststations 36. After testing, test trays 32 may be picked up at the end ofconveyor 38 by another operator. The test trays that are retrieved fromthe end of conveyor 38 may, as an example, be placed in a test tray cartor may be fed into additional systems.

Test stations 36 may provide test results to computing equipment such astest host 42 (e.g., one or more networked computers) for processing.Test host 42 may maintain a database of test results, may be used incontrolling the rate at which loading equipment 200 loads test traysonto conveyor belt 38 (e.g., by sending commands via path 41), may beused in sending test commands to test stations 36 (e.g., by sendingcommands via path 43), may track individual trays and devices under testas the trays and devices pass through system 30, and may perform othercontrol operations.

FIG. 4A is a diagram showing how device under test 10 may be receivedwithin test tray 32. As shown in FIG. 4A, test tray 32 may havesidewalls 100 that are configured to receive a device under test such asDUT 10. Device under test 10 may have one or more connector ports suchas port 28 (see, e.g., FIG. 1).

A pad extender such as pad extender 144 may have a mating connector suchas plug 146. Plug 146 may be configured to mate with a connector in port28 when DUT 10 has been mounted in test tray 32 and when pad extender144 has been moved towards DUT 10 in direction 148.

Following insertion of DUT 10 into test tray 32 and following insertionof plug connector 146 of pad extender 144 into connector 28 of DUT 10,test tray 32 of FIG. 4A may appear as shown in FIG. 4B. Pad extender 144may contain signal paths that connect pins in connector 28 tocorresponding contacts 62 on pad extender 144. Contacts 62 may beconfigured to mate with corresponding contacts coupled to tester 44and/or test host 42 during testing in system 30.

Because DUT 10 is connected to test contacts 62 in test tray 32 usingpad extender 144 associated with test tray 32, it is not necessary torepeatedly connect and disconnect device under test 10 from cabling ateach test station 36. Rather, connections between DUT 10 and the testequipment at each test station 36 by may be formed by coupling contacts62 in test tray 32 to corresponding contacts (e.g., spring-loaded pins)in each test station 36. By minimizing the number of times that cablesneed to be connected and disconnected from each device under test, thelife of tester cables and connectors may be extended.

The use of test tray 32 and loader 46 may allow DUT 10 to be placedaccurately within test stations 36 (e.g., with an accuracy of +/−0.1 mmor better, as an example). Test tray 32 may shield device under test 10from scratches and other damage during testing. In general, DUT 10 maybe received within test tray 32 in either an upwards facingconfiguration in which display 14 faces outwards away from tray 32 or adownwards facing configuration in which display 14 faces downwards ontothe base of test tray 32.

FIG. 5A is a perspective view of one suitable embodiment of test tray32. Tray 32 may be formed using non-marring material such as acetylplastic, Delrin® (a polyoxymethylene plastic), other plastics, or othersuitable non-marring materials. The use of non-marring materials mayhelp avoid scratches or other damage to DUT 10 when DUT 10 is placedwithin test tray 32. In the example of FIG. 5A, a layer of material 156may be formed to line the base of recess 154. As an example, material156 may be formed using the same material that is used to form tray 32.As another example, material 156 may be formed using elastomericmaterial such as rubberized foam. Material 156 may, in general, beformed using any suitable non-marring material.

Test tray 32 may be provided with guide structures configured toaccurately place device under test 10 in a desired location within arecess 154 in tray 32. As shown in FIG. 5A, a guide structure on the endof tray 32 may have an exposed end guide surface such as guide surface152. Guide structures on the side of tray 32 may have exposed side guidesurfaces such as guide surfaces 150.

FIG. 5C is a perspective view of test tray 32 after a device under testhas been inserted into test tray 32. As shown in FIG. 5C, test tray 32may have clamps 162 for holding device under test 10 within test tray32. The inner surfaces of clamps 162 may serve as guide surfaces 150(FIG. 5A).

Test tray 32 may also include engagement features such as holes 160formed on both ends of tray 32 (see, e.g., top perspective view of tray32 in FIG. 5A and bottom perspective view of tray 32 in FIG. 5B). Holessuch as holes 160 in test tray 32 or other engagement features may beconfigured to mate with corresponding engagement features on automatedloading equipment such as equipment 200 for loading test trays ontoconveyor belt 38 and loading equipment in each test station 36 forpicking up an incoming test tray for testing. For example, holes 160 maybe configured to receive corresponding pins from at least one roboticarm in loading equipment 200. The example of FIG. 5A, 5B, and 5C inwhich tray 32 includes eight holes for engaging with automated loadingequipment is merely illustrative. If desired, tray 32 may include atleast four holes, at least six holes, at least ten holes, etc.

FIG. 6 is a diagram showing one suitable configuration of loadingequipment 200. As shown in FIG. 6, loading equipment 200 may include afeed conveyor belt 270, a fixed test tray support fixture (sometimesreferred to herein as a temporary test tray dock or “pedestal”) 282, andloaders such as loaders 280 and 284.

Initially, a test system operator or automated loading equipment mayplace devices in test trays 32 onto conveyor belt 270 at location 290.Safety wall 268 may prevent the operator or automated loading equipmentfrom placing test tray 32 farther along conveyor 270. The height H ofsafety wall 268 may be configured so that only a single test tray 32 canpass between the upper surface of conveyor belt 270 and the lowersurface of safety wall 268 at a time. The presence of safety wall 268may therefore be used to ensure that there is only one layer of testtrays 32 on conveyor 270. The speed of conveyor 270 may be computercontrolled (if desired). Light sensor 272 may be used to monitor theflow of test trays 32 on conveyor 270. For example, conveyor 270 may runcontinuously until sensor 272 detects the presence of a test tray, atwhich point conveyor 270 may be temporarily halted to await unloadingusing loader 280. If desired, a tray stop structure such as tray stopstructure 400 may be placed at an end of conveyor 270 for guiding thetest tray to a desired position for pickup.

Loader 280 may be used to pick up test tray 32 from conveyor 270. Loader280 may include a computer-controlled positioner such as positioner 274and a grabber head such as grabber 276 that is positioned by positioner274. Positioner 274 may be controlled using commands sent from test host42 over path 41. Grabber 276 may contain computer-controlled actuatorsand engagement features such as pins that mate with correspondingengagement features such as holes 160 in test tray 32. Loader 280 may beused to move test trays 32 from conveyor belt 270 to pedestal 282.

As test tray 32 is being moved from conveyor 270 to pedestal 282, asensor such as sensor 273 may be used to identify the test tray. Forexample, sensor 202 may be a radio-frequency identification (RFID)sensor configured to identify a serial number associated with theincoming tray 32 and may forward the identified serial number to testhost 42 via path 41. Operated in this way, test host 42 may be used tokeep track of each test tray 32 that is provided to test system 30 fortesting.

Loader 280 may be configured to place an incoming test tray onto one ofmultiple possible locations on pedestal 282. In the example of FIG. 6,pedestal 282 includes first, second, and third regions on which testtrays 32 may be placed. Light-based sensors such as sensors 283-1,283-2, and 283-3 may be used to detect whether each of the three regionsis currently vacant. In particular, sensor 283-1 may be used todetermine whether a test tray is currently placed on the first region ofpedestal 282; sensor 283-2 may be used to determine whether a test trayis currently placed on the second region of pedestal 282; and sensor283-3 may be used to determine whether a test tray is currently placedon the third region of pedestal 282. Loader 280 may be configured toplace the incoming test tray onto a vacant region on pedestal 282. Ifall the regions on pedestal 282 are occupied, loader 280 may wait untilat least one region on pedestal 282 becomes available.

Loader 284 may be used to unload pedestal 282 (e.g., to move test trays32 from pedestal 282 to conveyor 38). Loader 284 may includecomputer-controlled positioner 286 and a grabber head such as grabber288 that is positioned by positioner 286. Positioner 286 may becontrolled using commands sent from test host 42 over path 41. Grabber288 may also contain computer-controlled actuators for grasping testtrays 32 (e.g., grabber 288 may also include engagement features such aspins that mate with corresponding holes 160 in test tray 32).

The speed of conveyor 38 is preferably fixed. At even time intervals(e.g., every 15 seconds plus or minus an allowed variation of a fewseconds), loader 284 may move a selected one of test trays 32 frompedestal 282 to end position 292 of conveyor belt 38, thereby ensuringthat test trays 32 are evenly spaced at a desired distance D from eachother along the surface of conveyor belt 38. Conveyor belt 38 may beused to convey test trays 32 to test stations 36 in test system 30 fortesting.

Pedestal 282 used as such may therefore serve as an input buffer fortest system 30. In general, the rate at which test trays are beingtransferred from conveyor 270 to pedestal 282 is at least equal to orgreater than the rate at which test trays are being transferred frompedestal 282 onto conveyor 38. This ensures that there is at least onetest tray on pedestal 282 at any given point in time available to bemoved onto conveyor 38 for optimal test throughput. The example of FIG.6 in which pedestal 282 provides three possible regions on which testtrays can be placed is merely illustrative. In other suitablearrangements, pedestal 282 may provide at least one test tray region, atleast two test tray regions, at least four test tray regions, etc. Anysuitable number of light-based sensors may be used to facilitatedetection of test trays on the different test tray regions.

Each of grabbers 276 and 288 may include a contractible member such asmember 402 that can be actuated using air-driven or motor-drivenactuators. FIG. 7 is a top view of an end portion of conveyor 270 intest system 30. Initially, DUT 10 and test tray 32 may be located on theleft hand side of conveyor belt 270. As conveyor belt 270 moves to theright, DUT 10 and test tray 32 may make physical contact withcorresponding guide surfaces of tray stop structure 400 (e.g., tray stopstructure 400 may help horizontally situate test tray 32 on the topsurface of conveyor 270 so that grabber 276 can properly engage withtest tray 32). Grabber 276 may have engagement features such as pins 404for mating with holes 160 in test tray 32.

When test tray 32 is ready to be picked up, grabber 276 may be loweredto a pick-up position so that pins 404 are aligned with test tray holes160. Initially, pins 404 may be held in a retracted position. After pins404 and holes 160 are aligned, actuators such as actuators 406 may beused to extend pins 404 into holes 160 (see, e.g., perspective view ofFIG. 9). Once grabber 276 has grasped test tray 32 in this way, grabber276 may deliver test tray 32 to pedestal 282.

FIG. 8 is a cross-sectional end view of grabber 276 showing howactuators may insert pins 404 into holes 160 in test tray 32 so thattest tray 32 may be picked up from conveyor belt 270. As with grabber276, grabber 288 may similarly be configured to grasp test tray 32 whentransporting test tray 32 from pedestal 282 to conveyor belt (e.g.,using actuator-driven pins 404 to engage with holes 160 on test tray32).

As shown in FIG. 10, loader 280 may include a horizontally extendingrail such as rail 300 and a vertically extending rail such as rail 302.Grabber 276 may travel up and down vertical rail 302 along vertical axisY. Vertical rail 302 may move laterally along rail 300 along horizontalaxis X. Loader 284 may likewise include horizontal and vertical rails.Grabber 288 may move up and down vertical rail 306. Rail 306 may movelaterally along rail 304.

In the configuration shown in FIG. 10, loader 280 is being used to pickup a test tray from conveyor 270 to deposit on pedestal 282, whereasloader 284 is being used to deposit a test tray that was picked up frompedestal 282 on conveyor 38. In the configuration shown in FIG. 11,loader 280 is using grabber 276 to deposit a test tray on pedestal 282,whereas loader 284 is being used to pick up a test tray from pedestal282 that is to be moved to conveyor 38.

The arrangement of FIGS. 6, 10, and 11 in which loading equipment 200includes two loaders 280 and 284 is merely illustrative and does notserve to limit the scope of the present invention. If desired, loadingequipment 200 may include a single loader 280 that can be used totransport test trays from conveyor 270 to pedestal 282 and to transporttest trays from pedestal 282 to conveyor 38 (see, e.g., FIGS. 12, 13,and 14). As shown in FIG. 12, loader 280 may include a horizontal railsuch as rail 300 that extends from the end portion of feed conveyor 270to a leading portion of conveyor 38. Loader 280 may also include avertically extending rail such as rail 302 that can travel along rail300 (parallel to axis X). Grabber 276 may travel up and down verticalrail 302 along vertical axis Y.

In the configuration shown in FIG. 12, loader 280 is being used to pickup a test tray from conveyor 270 to deposit on pedestal 282. In theconfiguration shown in FIG. 13, loader 280 is using grabber 276 todeposit a test tray on pedestal 282. In the configuration shown in FIG.14, loader 280 is using grabber 276 to deposit a test tray that has beenpicked up from pedestal 282 on conveyor 38.

Pedestal 282 as shown in FIGS. 10-14 having five possible regions forreceiving test trays is merely illustrative. In general, pedestal 282may include any number of test tray receiving regions, and any number ofloaders and associated grabbers may be used to transport test trays fromfeed conveyor 270 to pedestal 282 and from pedestal 282 to test conveyor38.

A flow chart of illustrative steps involved in using system 30 of FIG. 6is shown in FIG. 15. At step 310, an operator or automated loadingequipment may place one of test trays 32 on feed conveyor 270. Conveyor270 may move test tray 32 until sensor 272 detects the presence of testtray 32. Once sensor 272 detects test tray 32 (step 312), conveyor 270may be momentarily halted.

At step 314, grabber head 276 of loader 280 may be positioned over testtray 32. At step 316, grabber head 276 may be used to grab test tray 32.

At step 318, positioner 280 may move test tray 32 from conveyor 270 topedestal 282. At step 320, positioner 280 may release test tray 32 onpedestal 282. Once the test tray has been transferred from conveyor 270to pedestal 282 in this way, another test tray may be moved intoposition under sensor 272 using conveyor 270 (step 322).

As the test tray loading process of steps 310, 312, 314, 316, 318, 320,and 322 is being performed to load test trays onto pedestal 282, loader284 may be independently used to transfer test trays 32 from pedestal282 to conveyor 38 (step 324). In particular, loader 284 may, inresponse to control commands from a computer, move test trays 32 one ata time from pedestal 282 and to conveyor 38, depositing test trays 32 onconveyor 38 at desired time intervals (e.g., at a fixed time period ofabout 3 seconds). By loading test trays 32 onto conveyor 38 at fixedtime intervals, the spacing D between adjacent test trays may becontrolled (e.g., so that D has a fixed value of about 1 m). If desired,loader 280 may also be used to move test trays 32 from pedestal 282 toconveyor 38 in response to control commands from test host 42 (e.g.,second loader 284 need not be used).

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention. Theforegoing embodiments may be implemented individually or in anycombination.

What is claimed is:
 1. A method for operating a test system that is usedto test a plurality of electronic devices, wherein the test systemincludes a first conveyor belt, a second conveyor belt, and a fixedsupport structure, the method comprising: moving the plurality ofelectronic devices from the first conveyor belt to the fixed supportstructure at a first rate; moving the plurality of electronic devicesfrom the fixed support structure to the second conveyor belt at a secondrate that is at most equal to the first rate; and with test equipmentstationed along the second conveyor belt, testing the plurality ofelectronic devices.
 2. The method defined in claim 1, wherein theplurality of electronic devices comprises a plurality of handheldelectronic devices.
 3. The method defined in claim 1, wherein the secondrate is less than the first rate.
 4. The method defined in claim 1,wherein the test system further includes a computer-controlled loader,wherein moving the plurality of electronic devices from the firstconveyor belt to the fixed support structure comprises moving theplurality of electronic devices from the first conveyor belt to thefixed support structure with the computer-controlled loader, and whereinmoving the plurality of electronic devices from the fixed supportstructure to the second conveyor belt comprises moving the plurality ofelectronic devices from the fixed support structure to the secondconveyor belt with the computer-controlled loader.
 5. The method definedin claim 1, wherein the test system further includes first and secondcomputer-controlled loaders, wherein moving the plurality of electronicdevices from the first conveyor belt to the fixed support structurecomprises moving the plurality of electronic devices from the firstconveyor belt to the fixed support structure with the firstcomputer-controlled loader, and wherein moving the plurality ofelectronic devices from the fixed support structure to the secondconveyor belt comprises moving the plurality of electronic devices fromthe fixed support structure to the second conveyor belt with the secondcomputer-controlled loader.
 6. The method defined in claim 5, furthercomprising: installing the plurality of electronic devices withinrespective test trays, wherein the test trays include test trayengagement features, and wherein the computer-controlled loader includesloader engagement features configured to engage with the test trayengagement features; with a first sensor associated with the firstconveyor belt, detecting whether an incoming electronic device in theplurality of electronic devices is available to be moved from the firstconveyor belt to the fixed support structure by the firstcomputer-controlled loader; and with a second sensor, identifying aserial number associated with each test tray that is being moved fromthe first conveyor belt to the fixed support structure by the secondcomputer-controlled loader.
 7. The method defined in claim 4, furthercomprising: installing the plurality of electronic devices withinrespective test trays, wherein the test trays include test trayengagement features, and wherein the computer-controlled loader includesloader engagement features configured to engage with the test trayengagement features.
 8. The method defined in claim 7, wherein the testtray engagement features comprise holes, and wherein the loaderengagement features comprise pins.
 9. The method defined in claim 1,further comprising: with sensors associated with the fixed supportstructure, detecting whether or not the fixed support structure iscapable of receiving electronic devices from the first conveyor belt.10. The method defined in claim 1, further comprising: with a sensorassociated with the first conveyor belt, detecting whether an incomingelectronic device in the plurality of electronic devices is available tobe moved from the first conveyor belt to the fixed support structure.11. The method defined in claim 7, further comprising: with aradio-frequency identification sensor, identifying a serial numberassociated with each test tray that is being moved from the firstconveyor belt to the fixed support structure.
 12. A method for operatinga test system that is used to test a plurality of electronic devices,wherein the test system includes a test conveyor belt, a fixed supportstructure, and a loader, the method comprising: with the fixed supportstructure, receiving the plurality of electronic devices; with theloader, transferring the plurality of electronic devices from the fixedsupport structure to the test conveyor belt at predetermined timeintervals; and with test equipment stationed along the test conveyorbelt, testing the plurality of electronic devices.
 13. The methoddefined in claim 12, wherein the test system further includes a feedconveyor belt, the method further comprising: with the feed conveyorbelt, sequentially receiving the plurality of electronic devices; andwith the loader, transferring the received plurality of electronicdevices from the feed conveyor belt to the fixed support structure oneat a time.
 14. The method defined in claim 12, wherein the test systemfurther includes an additional loader and a feed conveyor belt, themethod further comprising: with the feed conveyor belt, sequentiallyreceiving the plurality of electronic devices; and with the additionalloader, transferring the received plurality of electronic devices fromthe feed conveyor belt to the fixed support structure one at a time. 15.The method defined in claim 12, further comprising: installing theplurality of electronic devices within respective test trays, whereinthe test trays include test tray engagement features.
 16. The methoddefined in claim 15, wherein the loader comprises a computer-controlledpositioner that controls a grabber, and wherein transferring theplurality of electronic devices from the fixed support structure to thetest conveyor belt comprises: with the grabber, picking up a selectedtest tray from the fixed support structure by engaging grabberengagement features of the grabber with the test tray engagementfeatures of the selected test tray; while the grabber engagementfeatures are engaged with the test tray engagement features,transporting the selected test tray from the fixed support structure tothe test conveyor belt; and with the grabber, depositing the selectedtest tray on the test conveyor belt by disengaging the grabberengagement features of the grabber from the test tray engagementfeatures of the selected test tray.
 17. A test system, comprising: afirst conveyor belt configured to receive a plurality of devices undertest; a fixed support structure configured to receive the plurality ofdevices under test from the first conveyor belt; a second conveyor belt;and a loader that is configured to move the devices under test from thefixed support structure to the second conveyor belt at fixed timeintervals.
 18. The test system defined in claim 17, wherein the loaderis further configured to move the plurality of devices under test fromthe first conveyor belt to the fixed support structure.
 19. The testsystem defined in claim 17, further comprising: an additional loaderthat is configured to move the plurality of devices under test from thefirst conveyor belt to the fixed support structure.
 20. The test systemdefined in claim 17, further comprising: a plurality of test trays eachof which is configured to house a device under tester in the pluralityof devices under test; and a safety wall positioned over the firstconveyor belt, wherein the safety wall is configured so that only asingle test tray can pass between an upper surface of first conveyorbelt and a lower surface of the safety wall at any given time.